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HashMap and LinkedHashMap CIP
Question 1
What is the default initial capacity of a HashMap?
- A
64
- B
32
- C
16
- D
None of these
Question 2
Which of the following statements is true about the HashMap class in Java?
- A
It maintains the insertion of the Map interface
- B
It is synchronized
- C
It is an implementation of the Map interface
- D
None of these
Question 3
Which of the following statements is true about the LinkedHashMap class in Java?
- A
It does not allow null keys or values.
- B
It is an implementation of the Map interface.
- C
It is an implementation of the HashMap interface.
- D
None of these
Question 4
What is the time complexity of the get() method in a HashMap in the worst case?
- A
O(1)
- B
O(n)
- C
O(n logn)
- D
O( log n )
Question 5
What is the syntax of creating a Hashmap in Java?
- A
HashMap<k, v> map = new HashMap<>();
- B
map<k, v> = new HashMap<>();
- C
HashMap<k, v> map = new HashMap();
- D
None of these
Question 6
How is LinkedHashMap declared in Java
- A
public class LinkedHashMap<K,V>
- B
public class LinkedHashMap<K,V> implements Map<K,V>
- C
public class LinkedHashMap<K,V> extends HashMap<K,V> implements Map<K,V>
- D
None of these
Question 7
What happens when a key-value pair already exists in the Map and we use put() to add the value associated with the same key?
- A
It adds one more key-value pair of the same key.
- B
It adds 2 values for the same key
- C
It throws an error
- D
It replaces the pre-existing value.
Question 8
What is the output of,
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
HashMap<String, Integer> m = new HashMap<String, Integer>();
m.put("gfg", 10);
m.put("ide", 16);
m.put("courses", 25);
System.out.print(m);
System.out.print(m.size());
for( Map.Entry< String, Integer >e: m.entrySet())
System.out.print(e.getKey() + " " + e.getValue());
}
}
- A
3courses 25gfg 10ide 16
- B
Error
- C
{courses=25, gfg=10, ide=16}3courses 25gfg 10ide 16
- D
None of these
Question 9
What is the output of the code,
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
HashMap<String, Integer> m = new HashMap<String, Integer>();
m.put("gfg", 10);
m.put("ide", 16);
m.put("courses", 25);
if( m.containsKey("ide"))
System.out.println("yes");
else
System.out.println("no");
m.remove("ide");
System.out.println(m.size());
}
}
- A
no
3
- B
yes
3
- C
yes
2
- D
no
2
Question 10
What is the output of the code,
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
LinkedHashMap<Integer, String> m = new LinkedHashMap<>();
m.put(10, "gfg");
m.put(16, "IDE");
m.put(25, "courses");
m.remove( 25 );
m.put( 20, "practice" );
System.out.println(m);
}
}
- A
Throws an error
- B
{10=gfg, 16=IDE, 20=practice}
- C
{10=gfg, 16=IDE, 25=courses, 20=practice}
- D
None of these
There are 10 questions to complete.
